H. D. Oldham — ^^sai/s in Theoretical Geology. 13 



shows that the pre-Tertiary disturbance was transverse, and did not 

 belong to that which has resulted in the elevation of the Himalayas- 

 It may be that in Kumaon and Garhwal this last had already 

 commenced when the Nummulitics were being deposited and only 

 extended to the north-west at a later period; but there is no 

 evidence to show that it could have commenced before the end of 

 the Secondary period ; and the early Palasozoic or still earlier date, 

 to which Mr. Middlemiss would seem inclined to refer the first 

 origin of the Himalayas as a mountain range, is, to say the least, 

 extremely improbable. 



Besides the stratigraphical evidence of the absence of disturbance, 

 there is everywhere, from the Jamu Hills to the outliers east of the 

 Ganges, a peculiar pisolitic, ferruginous bed, which invariably occurs 

 at the base of the Subathu group. In mineral and chemical character 

 this closely resembles the laterite of the Peninsula and the laterite 

 beds, which occur interbedded with the Nummulitics of Cutch and 

 Sind, and must probably be referred to the same source of origin. 

 The origin of the laterite of the Peninsula is still a vexed question, 

 which has been much complicated b}' the very loose manner in 

 which the term has been used ; but the balance of evidence seems 

 to show that the true laterite is in some way or other connected 

 with the Deccan Traps, and is directly or indirectly the result of 

 an alteration of them or their detritus. If this same source of 

 origin is accepted for the ferruginous bed at the base of the Subathu 

 group, it follows that the present distinction between Peninsular and 

 Extra-peninsular areas had not been established in Eocene times, 

 and, consequently, that the system of disturbance of which it is the 

 result must, at the outside, only have commenced when the Subathu 

 group was being deposited. 



In this connection the occurrence of Gondwana roclcs of Penin- 

 sular type in Sikkim and the Eastern Himalayas is important. 

 Unfortunately nothing is known of the great area of Nepaul, which 

 occupies the middle third of the length of the Himalayas ; but 

 Sikkim cannot in any way be regarded as a terminal area, and the 

 occurrence of Peninsular beds of latest Palceozoic or early Secondary 

 age ^ shows that the present limits between the Peninsular and 

 Himalayan ai-eas cannot have been established until the Secondary 

 period at the earliest. 



A further insight into the history of the commencement and 

 progress of the elevation of the Himalayas may be derived from a 

 study of the structure of the sub- Himalayan ranges. 



In the region west of the Jhelum the structure of the ground 

 does not enable us to decide with certainty at what date the 

 Himalayan system of disturbance invaded that area; but, so far 

 as can be judged, the beds appear to have undergone but little 

 compression till towards the end of the Tertiaiy period. 



In the Jamu Hills we find the typical sub-Himalayan structure 



1 Mallet, Mem. Geol. Surv. India, vol. xi. part i. ; see also Godwin-Austen, 

 Journ. Asiatic Soc. Bengal, part ii. vol. xxxviii. p. 151 ; La Touche, Eecords Geol. 

 Surv. India, vol. xviii. p. 121. 



